1. Field of the Invention
The present invention relates to a technique by which a wireless terminal and a wireless base station make a communication by using a wireless line.
2. Description of the Related Art
When a wireless terminal and a wireless base station make a communication by using a wireless line, the connection state of the wireless line is changed among three connection states such as active, dormant, and null states.
Here, the active state indicates a state in which the wireless base station and the wireless terminal make a communication by using a wireless line after the wireless base station authenticates the wireless terminal, or a state in which the wireless line is occupied and a communication can be immediately made although a communication is not made (namely, the state in which the wireless base station allocates the communication channel to the wireless terminal and a communication can be made).
The dormant state indicates a state in which the wireless line is released although the wireless base station and the wireless terminal maintain a communication state after the wireless base station authenticates the wireless terminal (namely, the state in which the communication channel is released and the logical connection of a network between the wireless base station and the wireless terminal is maintained).
The null state indicates a state in which the wireless line is released until the wireless base station calls the wireless terminal after the wireless terminal registers its position information to the wireless base station (namely, the state in which the communication channel is released and the logical connection of the network between the wireless base station and the wireless terminal is disconnected).
As is evident from the above definitions, a transition from the null state can be made only to the active state, a transition from the active state can be made to the dormant or the null state, and a transition from the dormant state can be made to the active or the null state.
Techniques for changing a connection state to a suitable state depending on a case are known.
For example, Japanese Patent Publication No. 2003-37874 discloses the technique for improving the use efficiency of a line by variably setting the threshold value of an inactivity timer for measuring a time from the completion of transmission/reception of a packet, namely, the value for changing a connection from an active state to a dormant state after the active state continues for the corresponding time depending on the type of data (electronic mail, stream data of a moving picture, etc.) to be transmitted/received.
Additionally, Japanese Patent Publication No. 2005-257312 discloses the technique for causing a navigation terminal device to be already changed to an active state at the time of actual transmission/reception of information, for example, by transmitting/receiving dummy information when an event (the start of destination setting, etc.) that is proved to transmit/receive the information soon is issued in a dormant state or a null state in the navigation terminal device. With the technique disclosed by this document, responsiveness to the transmission/reception of information can be improved.